Note: Descriptions are shown in the official language in which they were submitted.
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TOUCH PANEL DISPLAY
BACKGROUND OF THE INVENTION
Technical Field
The present invention relates to touch input devices. In
particular, to opto-matrix frames having a minimum component
count.
Background Art
Historically, keyboards were used to interact with
display devices. Due to the needs of particular users, a
number of alternative methods of interacting with display
de~ices were developed. Included in the alternatives were
items such as mice, light pens, tablets, joysticks, and the
like. All of these methods have the disadvantage of
requiring hardware extraneous to the display. The
development of touch panel displays provided an alternative
method of interacting with a display device which has the
additional advantage of not requiring hardware extraneous to
the display Touch panel displays allow a user to interact
by first presenting information on the screen. Then the
user interacts by touching the screen at locations based on
information displayed on the screen. The touch panel senses
the location of the finger or stylus and communicates that
information to the computer.
There are known alternative methods of designing touch
panel di~plays. One met~od u~es a transparent membrane
~witch which covers the surface o the displ~y screen Over
time, the membrane design creates vision problems for the
user. This is because the membrane lies directly over the
screen. Therefore, membrane wear will have a direct effect
on how well a user can see the display A preferable method
is the ~pto-matrix display This type of touch panel
display places nothing on the surface of the screen, elimi-
nating the problems caused by membrane wear. Further, the
frequency of energy used can be selected so that it is
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outside of the visible light range, thereby rendering the
matrix invisible to the user.
However, a disadvantage associated with opto-matrix
touch panel displays is the high component count and
conseguent high manufacturing expense. For example, a large
num~er of light emitting diodes (emitters) are required to
create the optical matrix. A correspondingly large number
of detectors, paired with corresponding emitters, are
required to detect light, or its absence, in the matrix.
Further, scanning the emitters and monitoring the detectors
typically requires significant on-board processing
capability to scan the emitter/detector pairs, measure the
difference between detector output before and after the
emitter is turned on, and determine if a stylus is present
at a given location. Touch panel displays also include
digital to analog converters to allow data to be converted
prior to being transferred to computers. Due to the
difference in strength of emitter signals and the difference
in sensitivity of detector output, errors can arise in the
form of false stylus detection or failure to detect a stylus
when present. Addressing the problems created by the
difference in emitter/ detector signals results in
additional hardware.
Some attempts have been made to reduce the number of
emitters and detectors required for the optical matrix in
the display. For example, U.S. patent ~,733,068 to Sherbeck
discloses a method of reducing the number of emitter~ by
placing emitters in th~ corners of the ~ezel with a
plurality of detectors on opposing sides of the bezel. This
approach allows the number of emitters to be reduced, but at
the same time prevents any reduction in the number of
detectors. Likewise, U.S, patent 4,766~424 to Adler et al
uses a similar approach by attaching a diode connected to a
light conducting strip to two sides of the beze~ and
ex~iting them with a plurality o emitters on the other two
sides of the ~ezel. This approach allows the numher of
detectors to be reduced but prevents any reduction in the
num~er of emitters. As a result, while attempts to reduce
the number of emitters and detectors have been successful~
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the very solutions to the problem of reducing the number of
emitters prevents reduction in the number of detectors, and
the ~olution to the problem of reducing the number of
detectors has prevented the reduction of both emitters.
Therefore, the prior art has not shown the ability to reduce
the number of emitters and detectors at the same time.
The prior art has failed to provide a touch panel input
device that not only has the known advantages of opto-matrix
displays, such as the absence o extraneous hardware, and
the superior visual qualities o opto-matrix touch panels
over membrane touch panel input devices, hut one which also
overcomes the disadvantages of known opto-matrix touch panel
devices, which results in high cost primarily due to the
number of components required to implement such a device and
in particular due to the large number of emitters and
detectors required to operate an optical touch panel
display, and the additional circuitry required to correct
differences in signal strength of emitters and detectors.
SUMMARY OF THE INVENTION
It is an object of this invention to reduce the number
of components in an optical input device to a number
heretofore unattainable.
It is another object of this invention to reduce the
required num~er of emitters and detectors in an optical
input device to one each.
It is a further object o~ this invention to tran~mit
energy to and from an optica~ input device with a i~er
optic ~un~le.
It is a still furt.her object of this invention to
control ~canninq of an optical energy field with optical
masks.
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These and other objects which will become apparent
during the discussion of the preferred embodiment are
accomplished by a system which uses a fiber optic bundle to
transmit energy from a single energy source such as an
emitter to the sides of a bezel and return detected energy
from opposite sides of the bezel to a single detector. A
transparent window in a darkened LCD mask is scanned across
the mask to move a beam of energy across the vertical and
horizontal planes of the display.
BRIEF ~ESCRIPTION OF THE DRAWINGS
Fig. 1 is a diagram showing an example of a prior art
approach to optical touch panels.
Fig. 2 shows a diagram of the components necessary to
implement the invention and their arrangement.
Fig. 3 is a simplified time diagram showing the
movement of the energy beam across the display.
DESCRIPTION OF THE PREFERRED EMBODIMENT
For ease of discussion, the following terms will be
used in this disclosure. The term "opto-matrix input
device" will be used interchangeably with the term "touch
panel" and "optical input device". The term "opa~ue point"
will be used interchangeably with the term "stylus." The
term "light" will be used interchangeably with "energy" or
"emitted energy" or "infra-red". A stylus can be anything
used to block the energy beam between an emitter and a
detector, such as a finger, pencil, or the like.
To ~etter understand the advantages of the current
invention, a brief discussion of a typical prior art
approach, as illustrated in Figure 1, will be presented
Referring to Fig. 1, the arrangement of components
around the front of a touch panel display bezel 100 are
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shown. The bezel 100 has left vertical side 102, a right
vertical side 106, a lower horizontal side 104, and an upper
horizontal side 108. Each side has a surface wide enough to
allow placement of emitters 110-158 and detectors 160-208 to
be mounted under the top surface 210 of the bezel 100. The
vertical and horizontal sides 102, 106, 104, 108,
respectively are made from material which allows transmitted
energy to pass through, thereby allowing an emitter 110-158
on one side of the bezel 100 to activate a corresponding
detector 160-208 on the opposite side of the bezel. Each
emitter i8 paired with the detector placed directly opposite
it in the bezel. By using conventional multiplexing
techniques, the emitter/detector pairs can be scanned one at
a time to determine if a stylus (not shown) is blocking
light transmitted from the emitter to the detector.
By way of example, if a stylus was placed on the touch
panel at location 216, then the light beam 212 from emitter
140 would be prevented from reaching detector 198.
Likewise, the light beam 214 from emitter 116 would be
prevented from reaching detector 172. As is well known in
the art, the location 216 of the stylus can be determined by
a simple process of calculation.
In order to determine the location of a stylus, prior
art systems require many emitter/detector pairs along with
other supp~rt circuitry (for example, circuitry required to
compensate for imbalances in emitter output or detector
sensitivity a~ well a~ circuitry required to detect and/or
correct defective emitters and detectors). As shown below,
the instant invention eliminates the need for all but a
single emitter/detector pair as well as the support
circuitry the additional emitters and detectors would
require.
Turning now to the invention, Figure 2 shows the basic
structure of the invention. As in prior art touch panel
displays, ~he components required to implement the invention
are integrated into the bezel 250. The ~ezel 250 also is
formed in the same manner as prior art systems with inner
suraces comprised of a left verticaL side 252, a right
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vertical side 256, a lower horizontal side 254, and an upper
horizontal side 258. The bezel sides 252-258 are also
manufactured from material which can transmit light to
enable energy transfer across the predetermined field
bounded by the beæel 250.
The light source consists of a single emitter 260.
Emitter 260 i8 activated continuously. The energy output by
the ~mitter 260 enters an emitter fiber-optic bundle 264.
The fibers in emitter fiber-optic bundle 264 are distributed
around one horizontal side and one vertical side of the
bezel 250. In the preferred embodiment, the fibers in
emitter fiber-optic bundle 264 are distributed around the
lower horizontal side 254 and the left vertical side 252
such that light output from the fibers can illuminate the
upper horizontal side 258 and the right vertical side 256
respectively. Those skilled in the art will recognize that
while the invention can be implemented with the fibers in
emitter fiber-optic bundle 264 arranged around the upper
horizontal side 258 rather than the lower horizontal ~ide
254, using the lower horizontal side 254 avoids any
interference from extraneous light energy. Thi~ is becau~e
overhead lighting in an office would provide more extraneous
light (i.e., noise) if the fiber~ in detector fiber-optic
bundle 266, used for receiving light, were in the lower
horizontal ~ide 254. The choice of left vertical side 252
versus right vertical side 256 for the fibers in emitter
fiber-optic bundle 264 is not important. In addition, each
fiber can be formed with a lens on the end of the fibers to
focus the light such that a more precise ~eam is directed
from one side of the ~ezel 2~0 to the other.
In a similar fashion, the fi~ers in detector
fiber-optic bundle 266 are arranged around the upper
horizontal side 258 and right vertical side 256. Light
output by the fibers in emitter fiber~optic bundle 264 are
aimed at fibers which are located directly across from the
emitting fibers. The fibers in detector fiber-optic bundle
266 receive light from the emitter fiber-optic bundle 264
and output that light to detector 262 ~or ease of
illustration, the circuitry u~ed to power the emitter 260
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and monitor the output of the detector 262 have been omitted
since that circuitry is old and well known in the art.
Those skilled in the art will recognize that while two
fiber-optic bundles 264, 266, are shown, a single bundle
whose fiberæ are appropriately routed could easily replace
the two fiber-optic bundles 264, 266, shown. In addition,
the emitter 260 and the detector 262 are shown outside of
the bezel 250 for ease of illustration, but can easily be
mounted in the bezel or elsewhere in the display.
Emitter LCD mask 270 is interposed between the output
of emitter fiber-optic bundle 264 and both left vertical
side 252 and lower horizontal side Z54. Likewise, detector
LCD mask 268 is interposed between the input of detector
fiber-optic bundle 266 and both right vertical side 256 and
upper horizontal side 258. Without the LCD masks 268, 270,
light would be transmitted along the length of both the
vertical sides 252, 256, and horizontal sides 254, 258,
which would make determination of the location of a stylus
impossible.
For ease of illustration, the multiplexor circuitry
(which is old and well known in the art) used to control the
LCD ma~k i~ not shown. The LCD masks 268, 270, are kept in
a darkened state to prevent light from crossing from left
vertical side 252 to right vertical side 256, and to prevent
light from crossing from lower horizontal side 254 to upper
horizontal side 258. In other words, the LCD masks block
energy transmission. The multiplexor circuitry scans a
transparent window across the LCD masks by unblocking a
~mall segment (i.e., turning a small segment of the LCD mas~
transparent) of the LCD mask to create a small window in
each LCD mask 268, 270 and synchronously moving the window
across the length of the mask. As æhown, emitter LCD mask
270 has a small window 274. Likewise, detector LCD mask 268
has a small window 272 The multiplexor circuitry controls
the mo~ement of windows 272, 274 such that they are located
directly across from one another as they scan across the
length of the LCD mask. By synchronously scanning the
windows 272, 274, a narrow beam of light 276 can be scanned
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across the display in alternating horizontal and vertical
directions with a ~ingle emitter/detector pair.
Those skilled in the art will recognize that several
variations in the scanning process can be made. For
example, scanning can vary in fre~uency by increasing the
scan rate when a stylus is detected. Likewise, adjacent
window locations can be skipped until a stylus is detected
and then scanning adjacent locations to determine the exact
location of the stylus.
Figure 3 is a time diagram which shows the movement of
the window acros~ the LCD mask~ 269, 270. For illustrati~e
purposes, five time points, T1 through T5 are shown. At
time T1, the energy beam is vertical and located on the
right side of the display. The multiplexor scans the LCD
masks 268, 270 such that the window moves to the left. At
time T2, the window has mo~ed farther to the left. At time
T3, the window has moved still farther. This process
continue~ until the window, and with it the energy beam,
scans the entire width of the display. When the energy beam
reache~ the left side of the display, the multiplexor begins
to scan the window~ up the length of the vertical sides of
the display. At time T4, the energy beam i~ shown at the
lower portion of the di~play. Later, at time T5, the window
has scanned upward to location T5. At the completion of one
full scan, the energy beam will have covered the display
area entirely, both in the vertical and horizontal
directions.
The location of a stylus is shown at 302. During the
vertical portion of the scan, the circuitry attached to the
detector 262 (shown in Figure 2~ would recog~ize the absence
of ener~y at time T2. Likewise, during the horizontal
portion of the scan, at time T5, the circuitry controlling
the detector 262 would also recognize the absence of energy.
Calculation of the ~ocation of the stylus at 302 from the
location of the beams at times T2 and T5 can ea3ily be done
by techniques well known in the art.
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While the invention has been described with respect to
a preferred embodiment thereof, it will be understood by
those skilled in the art that various changes in detail my
be made therein without departing from the spirit, scope,
and teaching of the invention. For example, although two
masks were used in the preferred embodiment, the invention
could be implemented with a single mask over the detector
fiber-optic bundle. Two or more emitters can be used to
provide light, thereby increasing display reliability by
allowing defective emitter replacement during scheduled
maintenance periods. For the same reason, two or more
detectors can be used. Separate multiplexor circuits for
the horizontal and vertical portions of the masks would
allow simultaneous vertical and horizontal scans, thereby
increasing scan rates. The invention can be implemented on
a display with an integrated bezel or on a bezel which is a
self-contained unit that can be attached to a separate
di~play device. Accordingly, the invention herein disclosed
is to be limited only as specified in khe following claims.
